一、準備
準備三臺服務器，或者在一臺服務器上啓動三個不同端口的mongodb服務
防火牆，開放對應的端口，否則會報錯
selinux設置關閉
二、mongodb搭建
#!/bin/bash
#This is a script to install mongidb, the version of mongodb is 3.4.0
#Download the installation package
wget https://fastdl.mongodb.org/linux/mongodb-linux-x86_64-3.4.0.tgz
tar zxvf mongodb-linux-x86_64-3.4.0.tgz -C /opt
cd /opt
mv mongodb-linux-x86_64-3.4.0 mongodb
Cat>>/etc/profile<<EOF
export MONGODB_HOME=/usr/local/mongodb
export PATH=$PATH:$MONGODB_HOME/bin
EOF
source /etc/profile
mkdir -p /opt/mongodb/data
mkdir -p /opt/mongodb/data/db
mkdir -p /opt/mongodb/data/logs
cd /opt/mongodb/data/logs
touch mongodb.log
cat>>/opt/mongodb/data1/mongodb.conf<<EOF
#端口號
port=27017
#數據目錄
dbpath=/opt/mongodb/data/db
#日誌目錄
logpath=/opt/mongodb/data/logs/mongodb.log
#以後臺方式運行
fork=true
#日誌輸出方式
logappend=true
#開啓認證
#auth=true
#副本集名稱
replSet=test
#本機IP
bind_ip=127.0.0.1
#操作文件最大值，單位 mb，默認硬盤百分之 5
oplogSize=10000
#不預先分配內存
noprealloc=true
EOF
cd /opt/mongodb/bin
./mongod --config /opt/mongodb/data/mongodb.conf
ln -s /opt/mongodb/bin/* /usr/bin/
按照這個安裝也可以，路徑改成自己想要安裝的路徑。
安裝完成
查看進程
ps -aux |grep mongod
我這個上面啓動了兩個mongo
是指定路徑，端口，配置文件啓動
啓動命令是
sudo mongod -f /opt/mongodb/data/mongodb.conf -dbpath /opt/mongodb/data/db -replSet LZAPP --bind_ip=10.10.100.186 --port=27017 &
設置開機啓動
vim /etc/rc.d/rc.local
添加
sudo mongod -f /opt/mongodb/data/mongodb.conf -dbpath /opt/mongodb/data/db -replSet test --bind_ip=10.10.100.186 --port=27017
修改 rc.local文件的的權限
chmod +x rc.local
重啓機器，測試看看
三、修改配置文件
port=27017 #啓動端口
#數據目錄
dbpath=/opt/mongodb/data/db #數據目錄
logpath=/opt/mongodb/data/logs/mongodb.log #日誌文件
#設置後臺運行
fork=true
#日誌輸出方式
logappend=true
#開啓認證
#auth=true
bind_ip=10.10.100.186 #本機IP，這個一定要寫
replSet=test #副本集名稱
四、初始化副本集
在三個節點中的任意一個節點機上操作（比如在10.10.100.186節點機）
登錄mongodb
mongo 10.10.100.177:27017
登錄admin數據庫
>use admin
switched to db admin
#定義副本集配置變量，這裏的 _id:”repset” 和上面命令參數“ –replSet repset” 要保持一樣。
> config={_id:"test",members:[{_id:0,host:"10.10.100.186:27018"},{_id:1,host:"10.10.100.187:27018"},{_id:2,host:"10.10.100.188:27018"}]}
{
"_id" : "test",
"members" : [
{
"_id" : 0,
"host" : "10.10.100.186:27018"
},
{
"_id" : 1,
"host" : "10.10.100.187:27018"
},
{
"_id" : 2,
"host" : "10.10.100.188:27018"
}
]
}
初始化副本集配置
> rs.initiate(config)
{ "ok" : 1 }
返回1，是正常，返回0，就是失敗
查看副本集配置
test:OTHER> rs.conf()
{
"_id" : "test",
"version" : 1,
"protocolVersion" : NumberLong(1),
"members" : [
{
"_id" : 0,
"host" : "10.10.100.186:27018",
"arbiterOnly" : false,
"buildIndexes" : true,
"hidden" : false,
"priority" : 1,
"tags" : {
},
"slaveDelay" : NumberLong(0),
"votes" : 1
},
{
"_id" : 1,
"host" : "10.10.100.187:27018",
"arbiterOnly" : false,
"buildIndexes" : true,
"hidden" : false,
"priority" : 1,
"tags" : {
},
"slaveDelay" : NumberLong(0),
"votes" : 1
},
{
"_id" : 2,
"host" : "10.10.100.188:27018",
"arbiterOnly" : false,
"buildIndexes" : true,
"hidden" : false,
"priority" : 1,
"tags" : {
},
"slaveDelay" : NumberLong(0),
"votes" : 1
}
],
"settings" : {
"chainingAllowed" : true,
"heartbeatIntervalMillis" : 2000,
"heartbeatTimeoutSecs" : 10,
"electionTimeoutMillis" : 10000,
"catchUpTimeoutMillis" : 2000,
"getLastErrorModes" : {
},
"getLastErrorDefaults" : {
"w" : 1,
"wtimeout" : 0
},
"replicaSetId" : ObjectId("5d6db54279053540497f68c8")
}
}
#查看集羣節點的狀態
test:PRIMARY> rs.status();
{
"set" : "test",
"date" : ISODate("2019-09-03T00:36:45.238Z"),
"myState" : 1,
"term" : NumberLong(1),
"heartbeatIntervalMillis" : NumberLong(2000),
"optimes" : {
"lastCommittedOpTime" : {
"ts" : Timestamp(1567470995, 1),
"t" : NumberLong(1)
},
"appliedOpTime" : {
"ts" : Timestamp(1567470995, 1),
"t" : NumberLong(1)
},
"durableOpTime" : {
"ts" : Timestamp(1567470995, 1),
"t" : NumberLong(1)
}
},
"members" : [
{
"_id" : 0,
"name" : "10.10.100.186:27018",
"health" : 1,
"state" : 1,
"stateStr" : "PRIMARY",
"uptime" : 213,
"optime" : {
"ts" : Timestamp(1567470995, 1),
"t" : NumberLong(1)
},
"optimeDate" : ISODate("2019-09-03T00:36:35Z"),
"infoMessage" : "could not find member to sync from",
"electionTime" : Timestamp(1567470924, 1),
"electionDate" : ISODate("2019-09-03T00:35:24Z"),
"configVersion" : 1,
"self" : true
},
{
"_id" : 1,
"name" : "10.10.100.187:27018",
"health" : 1,
"state" : 2,
"stateStr" : "SECONDARY",
"uptime" : 90,
"optime" : {
"ts" : Timestamp(1567470995, 1),
"t" : NumberLong(1)
},
"optimeDurable" : {
"ts" : Timestamp(1567470995, 1),
"t" : NumberLong(1)
},
"optimeDate" : ISODate("2019-09-03T00:36:35Z"),
"optimeDurableDate" : ISODate("2019-09-03T00:36:35Z"),
"lastHeartbeat" : ISODate("2019-09-03T00:36:45.077Z"),
"lastHeartbeatRecv" : ISODate("2019-09-03T00:36:43.544Z"),
"pingMs" : NumberLong(0),
"syncingTo" : "10.10.100.186:27018",
"configVersion" : 1
},
{
"_id" : 2,
"name" : "10.10.100.188:27018",
"health" : 1,
"state" : 2,
"stateStr" : "SECONDARY",
"uptime" : 90,
"optime" : {
"ts" : Timestamp(1567470995, 1),
"t" : NumberLong(1)
},
"optimeDurable" : {
"ts" : Timestamp(1567470995, 1),
"t" : NumberLong(1)
},
"optimeDate" : ISODate("2019-09-03T00:36:35Z"),
"optimeDurableDate" : ISODate("2019-09-03T00:36:35Z"),
"lastHeartbeat" : ISODate("2019-09-03T00:36:45.077Z"),
"lastHeartbeatRecv" : ISODate("2019-09-03T00:36:43.543Z"),
"pingMs" : NumberLong(0),
"syncingTo" : "10.10.100.186:27018",
"configVersion" : 1
}
],
"ok" : 1
}
五、測試Mongodb副本集數據複製功能 <mongodb默認是從主節點讀寫數據的，副本節點上不允許讀，需要設置副本節點可以讀>
1）在主節點建立數據庫，插入測試數據
test:PRIMARY> use test;
switched to db test
test:PRIMARY> db.testdb.insert({"test1":"testval1"})
WriteResult({ "nInserted" : 1 })
2）在從節點查看數據是否複製過來
登錄數據庫
mongo 10.10.100.187:27017
test:SECONDARY> use test;
switched to db test
test:SECONDARY> show tables;
2019-09-03T08:40:09.371+0800 E QUERY [main] Error: listCollections failed: {
"ok" : 0,
"errmsg" : "not master and slaveOk=false",
"code" : 13435,
"codeName" : "NotMasterNoSlaveOk"
} :
_getErrorWithCode@src/mongo/shell/utils.js:25:13
DB.prototype._getCollectionInfosCommand@src/mongo/shell/db.js:805:1
DB.prototype.getCollectionInfos@src/mongo/shell/db.js:817:19
DB.prototype.getCollectionNames@src/mongo/shell/db.js:828:16
shellHelper.show@src/mongo/shell/utils.js:748:9
shellHelper@src/mongo/shell/utils.js:645:15
@(shellhelp2):1:1
上面出現了報錯！
這是因爲mongodb默認是從主節點讀寫數據的，副本節點上不允許讀，需要設置副本節點可以讀
test:SECONDARY> db.getMongo().setSlaveOk(); 設置一下
test:SECONDARY> show tables; 就可以讀出來了，兩臺都需要設置一下
testdb
現在，把主節點宕掉，登錄另外的節點，查看副本集的狀態
test:PRIMARY> rs.status();
{
"set" : "test",
"date" : ISODate("2019-09-03T00:46:21.057Z"),
"myState" : 1,
"term" : NumberLong(2),
"heartbeatIntervalMillis" : NumberLong(2000),
"optimes" : {
"lastCommittedOpTime" : {
"ts" : Timestamp(1567471577, 1),
"t" : NumberLong(2)
},
"appliedOpTime" : {
"ts" : Timestamp(1567471577, 1),
"t" : NumberLong(2)
},
"durableOpTime" : {
"ts" : Timestamp(1567471577, 1),
"t" : NumberLong(2)
}
},
"members" : [
{
"_id" : 0,
"name" : "10.10.100.186:27018",
"health" : 1,
"state" : 2,
"stateStr" : "SECONDARY",
"uptime" : 34,
"optime" : {
"ts" : Timestamp(1567471577, 1),
"t" : NumberLong(2)
},
"optimeDurable" : {
"ts" : Timestamp(1567471577, 1),
"t" : NumberLong(2)
},
"optimeDate" : ISODate("2019-09-03T00:46:17Z"),
"optimeDurableDate" : ISODate("2019-09-03T00:46:17Z"),
"lastHeartbeat" : ISODate("2019-09-03T00:46:20.494Z"),
"lastHeartbeatRecv" : ISODate("2019-09-03T00:46:19.899Z"),
"pingMs" : NumberLong(0),
"syncingTo" : "10.10.100.188:27018",
"configVersion" : 1
},
{
"_id" : 1,
"name" : "10.10.100.187:27018",
"health" : 1,
"state" : 2,
"stateStr" : "SECONDARY",
"uptime" : 664,
"optime" : {
"ts" : Timestamp(1567471577, 1),
"t" : NumberLong(2)
},
"optimeDurable" : {
"ts" : Timestamp(1567471577, 1),
"t" : NumberLong(2)
},
"optimeDate" : ISODate("2019-09-03T00:46:17Z"),
"optimeDurableDate" : ISODate("2019-09-03T00:46:17Z"),
"lastHeartbeat" : ISODate("2019-09-03T00:46:20.462Z"),
"lastHeartbeatRecv" : ISODate("2019-09-03T00:46:19.161Z"),
"pingMs" : NumberLong(0),
"syncingTo" : "10.10.100.188:27018",
"configVersion" : 1
},
{
"_id" : 2,
"name" : "10.10.100.188:27018",
"health" : 1,
"state" : 1,
"stateStr" : "PRIMARY",
"uptime" : 724,
"optime" : {
"ts" : Timestamp(1567471577, 1),
"t" : NumberLong(2)
},
"optimeDate" : ISODate("2019-09-03T00:46:17Z"),
"infoMessage" : "could not find member to sync from",
"electionTime" : Timestamp(1567471486, 1),
"electionDate" : ISODate("2019-09-03T00:44:46Z"),
"configVersion" : 1,
"self" : true
}
],
"ok" : 1
}
發現當原來的主節點10.10.100.186宕掉後，經過選舉，原來的從節點10.10.100.188被推舉爲新的主節點。
然後在新的節點插入數據
test:PRIMARY> for(var i=0;i<10000;i++){db.test.insert({"name":"test"+i,"age":123})}
WriteResult({ "nInserted" : 1 })
test:PRIMARY>
登錄從節點查看數據是否同步
test:SECONDARY> db.test.find()
{ "_id" : ObjectId("5d6db9ce460b07bcce150716"), "name" : "test0", "age" : 123 }
{ "_id" : ObjectId("5d6db9ce460b07bcce150718"), "name" : "test2", "age" : 123 }
{ "_id" : ObjectId("5d6db9ce460b07bcce150717"), "name" : "test1", "age" : 123 }
{ "_id" : ObjectId("5d6db9ce460b07bcce15071b"), "name" : "test5", "age" : 123 }
{ "_id" : ObjectId("5d6db9ce460b07bcce15071e"), "name" : "test8", "age" : 123 }
{ "_id" : ObjectId("5d6db9ce460b07bcce150719"), "name" : "test3", "age" : 123 }
{ "_id" : ObjectId("5d6db9ce460b07bcce15071c"), "name" : "test6", "age" : 123 }
{ "_id" : ObjectId("5d6db9ce460b07bcce15071d"), "name" : "test7", "age" : 123 }
{ "_id" : ObjectId("5d6db9ce460b07bcce15071a"), "name" : "test4", "age" : 123 }
{ "_id" : ObjectId("5d6db9ce460b07bcce150720"), "name" : "test10", "age" : 123 }
{ "_id" : ObjectId("5d6db9ce460b07bcce15071f"), "name" : "test9", "age" : 123 }
{ "_id" : ObjectId("5d6db9ce460b07bcce150721"), "name" : "test11", "age" : 123 }
{ "_id" : ObjectId("5d6db9ce460b07bcce150722"), "name" : "test12", "age" : 123 }
{ "_id" : ObjectId("5d6db9ce460b07bcce15072b"), "name" : "test21", "age" : 123 }
{ "_id" : ObjectId("5d6db9ce460b07bcce150725"), "name" : "test15", "age" : 123 }
{ "_id" : ObjectId("5d6db9ce460b07bcce150728"), "name" : "test18", "age" : 123 }
{ "_id" : ObjectId("5d6db9ce460b07bcce15072a"), "name" : "test20", "age" : 123 }
{ "_id" : ObjectId("5d6db9ce460b07bcce150726"), "name" : "test16", "age" : 123 }
{ "_id" : ObjectId("5d6db9ce460b07bcce150729"), "name" : "test19", "age" : 123 }
{ "_id" : ObjectId("5d6db9ce460b07bcce150727"), "name" : "test17", "age" : 123 }
發現數據已經同步
六、Mongodb讀寫分離
目前來看。Mongodb副本集可以完美支持故障轉移。至於主節點的讀寫壓力過大如何解決？常見的解決方案是讀寫分離。
一般情況下，常規寫操作來說並沒有讀操作多，所以在Mongodb副本集中，一臺主節點負責寫操作，兩臺副本節點負責讀操作。
1）設置讀寫分離需要先在副本節點SECONDARY 設置 setSlaveOk。
2）在程序中設置副本節點負責讀操作，如下代碼：<br>
public class TestMongoDBReplSetReadSplit {
public static void main(String[] args) {
try {
List<ServerAddress> addresses = new ArrayList<ServerAddress>();
ServerAddress address1 = new ServerAddress("10.10.100.186" , 27017);
ServerAddress address2 = new ServerAddress("10.10.100.187" , 27017);
ServerAddress address3 = new ServerAddress("10.10.100.188" , 27017);
addresses.add(address1);
addresses.add(address2);
addresses.add(address3);
MongoClient client = new MongoClient(addresses);
DB db = client.getDB( "test" );
DBCollection coll = db.getCollection( "testdb" );
BasicDBObject object = new BasicDBObject();
object.append( "test2" , "testval2" );
//讀操作從副本節點讀取
ReadPreference preference = ReadPreference. secondary();
DBObject dbObject = coll.findOne(object, null , preference);
System. out .println(dbObject);
} catch (Exception e) {
e.printStackTrace();
}
}
}
讀參數除了secondary一共還有五個參數：primary、primaryPreferred、secondary、secondaryPreferred、nearest。
primary：默認參數，只從主節點上進行讀取操作；
primaryPreferred：大部分從主節點上讀取數據,只有主節點不可用時從secondary節點讀取數據。
secondary：只從secondary節點上進行讀取操作，存在的問題是secondary節點的數據會比primary節點數據“舊”。
secondaryPreferred：優先從secondary節點進行讀取操作，secondary節點不可用時從主節點讀取數據；
nearest：不管是主節點、secondary節點，從網絡延遲最低的節點上讀取數據。
讀寫分離做好後，就可以進行數據分流，減輕壓力，解決了"主節點的讀寫壓力過大如何解決？"這個問題。不過當副本節點增多時，主節點的複製壓力會加大有什麼辦法解決嗎？基於這個問題，Mongodb已有了相應的解決方案 - 引用仲裁節點：
在Mongodb副本集中，仲裁節點不存儲數據，只是負責故障轉移的羣體投票，這樣就少了數據複製的壓力。看起來想的很周到啊，其實不只是主節點、副本節點、仲裁節點，還有Secondary-Only、Hidden、Delayed、Non-Voting，其中：
Secondary-Only：不能成爲primary節點，只能作爲secondary副本節點，防止一些性能不高的節點成爲主節點。
Hidden：這類節點是不能夠被客戶端制定IP引用，也不能被設置爲主節點，但是可以投票，一般用於備份數據。
Delayed：可以指定一個時間延遲從primary節點同步數據。主要用於備份數據，如果實時同步，誤刪除數據馬上同步到從節點，恢復又恢復不了。
Non-Voting：沒有選舉權的secondary節點，純粹的備份數據節點。